Pasteurized liquid whole egg products have been used for many years to replace shell eggs. Liquid whole egg products have generally been considered to be more convenient for use, especially on a large scale. Commercial egg products must be subjected to pasteurization processes to produce a pathogen-free food.
Pasteurization of egg products have been mandated by regulations in the United States and other countries so that the egg product is free of pathogenic bacteria. In the United States pasteurization is generally conducted at 140 degrees Fahrenheit (60.degree. C.) for a period of at least 3.5 minutes. The objective of pasteurization of an egg product is to produce a salmonellae-negative product, although the number of other microorganisms is also reduced by this process.
Reference is made to an article by P. M. Foegeding and N. W. Stanley, "Growth and Inactivation of Microorganisms Isolated From Ultrapasteurized Egg," Journal of Food Science, Vol. 52, No. 5, 1987, pp. 1219-1227, which indicates that there are several types of microorganisms found in raw egg products. For example, Pseudomonas sp, enterococcus sp, B circulans, and B. cereus isolate, are among such microorganisms which may be isolated from raw liquid whole egg.
There have also been many types and kinds of apparatuses and processes for pasteurizing food products. For example reference may be made to the following foreign patent U.K. Patent No. 2,278,992A and U.S. Pat. Nos.: 2,565,311; 2,936,240; 3,232,769; 3,404,008; 3,579,631; 3,615,659; 3,738,847; 3,843,825; 4,490,401; 4,511,589; 4,627,984; 4,946,041; 5,019,408; 5,048,404; and article by H. R. Ball, Jr. et al., "Functionality and Microbial Stability of Ultrapasteurized, Aseptically Packaged Refrigerated Whole Egg," Journal of Food Science, Vol. 52, No. 5, 1987, P. 1212-1218.
Pasteurized liquid whole egg products with long shelf-life have been produced in the United States according to the teachings of several patents by Swartzel et al. and others as indicated above. The article by H. R. Ball, Jr. et al., describes a pasteurization process for liquid whole eggs where pasteurized product is subsequently aseptically packaged. Long shelf-life liquid pasteurized eggs are more convenient and have a better quality than frozen or dried egg products.
While such a process pasteurizes the egg, the aseptic packaging technique is restrictive in that only certain size and type of packages may be employed with apparatuses designed to achieve this task.
Therefore, it would be highly desirable to have a new and improved technique for pasteurizing raw liquid egg and egg products that do not require aseptic packaging. Such a new and improved process should also permit the pasteurized liquid egg and liquid egg product to be packaged in different types and kinds of packaging, including packaging of different sizes and volumes.
Therefore, it would be highly desirable to have a new and improved technique for pasteurizing raw liquid egg and liquid egg products that do not require aseptic packaging. Such a new and improved process should also permit the pasteurized liquid egg and liquid egg products to be packaged in different types and kinds of packaging, include packaging of different sizes and volumes.
U.S. Pat. Nos. 2,565,311 and 2,936,240 describe prior art whole egg pasteurization processes in which the steps of heating, chilling, and packaging occur in that order.
U.S. Pat. No. 3,232,769 shows a method of preparing eggs and food products in which the whites and yolks of eggs are separated, cooked, and then mixed with salad ingredients and lactic acid to adjust the pH of the mixture. Packaging and sealing occur followed by heating to a temperature of 170 degrees Fahrenheit to destroy harmful agents. This process essentially cooks the product, therefore it cannot be used to substitute liquid whole eggs.
U.S. Pat. Nos. 3,404,008; 3,579,631; and 4,511,589 teach processes pasteurizing egg products which employ heat exchangers. Pasteurized egg products are packaged following the use of the apparatuses shown in these references. It has been found that heat exchangers tend to foul during such processes, although successful in pasteurizing the raw egg product.
U.S. Pat. No. 5,167,976 teaches a method of extending the shelf life of liquid egg product by employing a two step heating process followed by cooling and packaging.
U.S. Pat. Nos. 3,843,813 and 5,290,583 show radio frequency and electroheating techniques applied to pasteurization of liquid egg products.
U.S. Pat. No. 4,994,291 reveals a method of ultrapasteurizing liquid whole egg product employing time and temperature parameters. In this reference, liquid whole egg product is subjected to heat treatment described by an equivalent temperature method followed by aseptically packaging the liquid whole egg product. Applicant incorporates by reference U.S. Pat. No. 4,994,291 in its entirety in the present application.
Perhaps the most promising method and apparatus is disclosed in Great Britain patent GB 2,278,992. The GB patent discloses a method and apparatus where unpasteurized or pasteurized liquid egg is placed in a non-aseptic container that is then sealed and heated to a pasteurization temperature of between about 140 degrees Fahrenheit and 155 degrees Fahrenheit and maintained for a predetermined period of time between about three minutes and about 30 minutes depending upon the initial pasteurization state of the liquid egg product.
While such a technique may help extend the shelf life of raw egg and raw liquid egg products, application of the technique is relatively expensive, and does not help throughput. In this regard, the cold fill system as disclosed in the Great Britain patent 2,278,992 requires a long come-up time for the production throughput when the product and package are heated by conventional means. Moreover, while the application of other heating techniques such as radio frequency, microwave or heating by applying electricity may help increase throughput, such heating techniques are generally more expensive and require special types and kinds of heating equipment.
For example, a one liter package of eggs at 40 degrees Fahrenheit requires about 30 to 45 minutes of heating time to reach a temperature of between about 145 degrees Fahrenheit and about 155 degrees Fahrenheit. Thus, such a heating time requires a very lengthy heating tunnel, if the process is carried out on a commercial basis. Such a long heating tunnel not only significantly increases processing time, but also requires a significant "come-up" time to reach a desired pasteurization temperature such a slow come-up time also may well damage the quality of the egg and may well not permit the egg product to be heated to a pasteurization temperature above 155 degrees Fahrenheit. Also, if larger packages are utilized in a long tunnel, throughput time is further decreased due to the larger volumes of product to be pasteurized.
Therefore, it would be highly desirable to have a new and improved processing technique for extending the shelf life of a liquid egg and liquid egg products. Such a new and improved processing technique should significantly increase throughput and thus, help reduce the costs for processing such liquid egg products.
A method for processing liquid egg products which overcomes the disadvantages found in the prior art methods and apparatuses would be a notable advance in the food processing field.